using System.Reflection;
using System.Text.Json;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using StabilityMatrix.Core.Extensions;
using StabilityMatrix.Core.Helper;
using StabilityMatrix.Core.Models.Configs;
using StabilityMatrix.Core.Models.Progress;
using StabilityMatrix.Core.Models.Update;
using StabilityMatrix.Core.Services;

namespace StabilityMatrix.Core.Updater;

public class UpdateHelper : IUpdateHelper
{
    private readonly ILogger<UpdateHelper> logger;
    private readonly IHttpClientFactory httpClientFactory;
    private readonly IDownloadService downloadService;
    private readonly DebugOptions debugOptions;
    private readonly System.Timers.Timer timer = new(TimeSpan.FromMinutes(5));
    
    private string UpdateManifestUrl => debugOptions.UpdateManifestUrl ??
        "https://cdn.lykos.ai/update.json";
    
    private static readonly string UpdateFolder =
        Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Update");

    public static readonly string ExecutablePath =
        Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Update", "StabilityMatrix.exe");

    public UpdateHelper(ILogger<UpdateHelper> logger, IHttpClientFactory httpClientFactory,
        IDownloadService downloadService, IOptions<DebugOptions> debugOptions)
    {
        this.logger = logger;
        this.httpClientFactory = httpClientFactory;
        this.downloadService = downloadService;
        this.debugOptions = debugOptions.Value;
        
        timer.Elapsed += async (_, _) => { await CheckForUpdate(); };
    }

    public async Task StartCheckingForUpdates()
    {
        timer.Enabled = true;
        timer.Start();
        await CheckForUpdate();
    }

    public async Task DownloadUpdate(UpdateInfo updateInfo,
        IProgress<ProgressReport> progress)
    {
        var downloadUrl = updateInfo.DownloadUrl;

        Directory.CreateDirectory(UpdateFolder);
        
        // download the file from URL
        await downloadService.DownloadToFileAsync(downloadUrl, ExecutablePath, progress: progress,
            httpClientName: "UpdateClient");
    }


    /// <summary>
    /// Data for use in signature verification.
    /// Semicolon separated string of fields:
    /// "version, releaseDate, channel, type, url, changelog, hashBlake3"
    /// </summary>
    private string GetUpdateInfoSignedData(UpdateInfo updateInfo)
    {
        var channel = updateInfo.Channel.GetStringValue().ToLowerInvariant();
        var date = updateInfo.ReleaseDate.ToString("yyyy-MM-ddTHH:mm:ss.ffffffzzz");
        return $"{updateInfo.Version};{date};{channel};" +
               $"{(int) updateInfo.Type};{updateInfo.DownloadUrl};{updateInfo.ChangelogUrl};" +
               $"{updateInfo.HashBlake3}";
    }

    private async Task CheckForUpdate()
    {
        try
        {
            var httpClient = httpClientFactory.CreateClient("UpdateClient");
            var response = await httpClient.GetAsync(UpdateManifestUrl);
            if (!response.IsSuccessStatusCode)
            {
                logger.LogError("Error while checking for update");
                return;
            }

            var updateInfo =
                await JsonSerializer.DeserializeAsync<UpdateInfo>(
                    await response.Content.ReadAsStreamAsync());

            if (updateInfo == null)
            {
                logger.LogError("UpdateInfo is null");
                return;
            }
            logger.LogInformation("UpdateInfo signature: {Signature}", updateInfo.Signature);
            
            var updateInfoSignData = GetUpdateInfoSignedData(updateInfo);
            logger.LogInformation("UpdateInfo signed data: {SignData}", updateInfoSignData);
            
            // Verify signature
            var checker = new SignatureChecker();
            if (!checker.Verify(updateInfoSignData, updateInfo.Signature))
            {
                logger.LogError("UpdateInfo signature is invalid: {Info}", updateInfo);
                return;
            }
            logger.LogInformation("UpdateInfo signature verified");

            var currentVersion = Assembly.GetExecutingAssembly().GetName().Version;

            if (updateInfo.Version <= currentVersion)
            {
                logger.LogInformation("No update available");
                return;
            }

            logger.LogInformation("Update available");
            EventManager.Instance.OnUpdateAvailable(updateInfo);
        }
        catch (Exception e)
        {
            logger.LogError(e, "Couldn't check for update");
        }
    }
}